Background: After major surgeries, such as abdominal or thoracic surgery, the majority of patients experience moderate to severe pain that may not be optimally controlled. Inadequate pain relief may lead to complications that can hinder rehabilitation and slow recovery.

Background: Acute Kidney Injury (AKI) is a prevalent and important complication of cardiac surgery, which is associated with significant morbidity and mortality. Identification of risk factors associated with AKI will help it's prevent. Objectives: The objective of the present investigation was to identify risk factors for acute kidney injury in patients who underwent coronary artery bypass graft (CABG) surgery at a tertiary care center for cardiovascular patients in Iran. Patients and Methods: From March 2014 to April 2015, 490 consecutive patients who underwent On-pump CABG at Rajaie cardiovascular medical and research center were assessed. Baseline variables and perioperative data were collected and their association with the development of AKI was evaluated. Results: Patients' mean age was of 67.9 (SD = 12.5) years. From these patients 353 (72%) were male and 137 (28%) were female. Six deaths (1.3%) occurred among patients. Thirteen patients (2%) had AKI. The baseline serum creatinine concentrations in patients with AKI were significantly higher than other patients (P = 0.04). Volume of transfused red blood cells and hemoglobin value were different, associated with AKI (P < 0.05), while systemic arterial oxygen saturation and pressure values were not associated with AKI (P > 0.05). Mean arterial pressure (MAP) was not different in patients with AKI (P = 0.85). The mean pump time in patients with AKI was significantly higher than the other patients (P = 0.02). Postoperative Left ventricle ejection fraction (LVEF) in patients who developed AKI was significantly reduced compared with patients without AKI (P = 0.01). The in-hospital mortality of patients who developed AKI was 7.69% compared with 1.04% among those who did not (P = 0. 01). Conclusions: Acute kidney injury is the important postoperative organ dysfunction in patients who underwent CABG and preoperative elevated serum creatinine concentration, cardiopulmonary bypass time > 120 minutes, intraoperative anemia and blood transfusion were serious risk factors associated with AKI.